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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 5:36 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Sheboygan, Wisconsin
I have a radio that calls for a 5Z4MG rectifier. <BR>I can find info on 5Z4 tubes and I have a NOS metal 5Z4 tube (National Union if I remember right)without the letters "MG" on the tube after the "5Z4". I was wondering what the "MG" after the 5Z4 is all about. I found some info on tube numbering and codes but nothing about what the "MG" could mean. <P>Thanks,<BR>Ron <P>------------------<BR><P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 5:40 am 
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MG = metal glass, a metal shell over a glass tube. <P>It's a rectifier. A regular 5Z4 will work fine, a 5Y3 will work also.<P>------------------<BR>Paul<P> <A HREF="http://personalpages.tds.net/~pdieten" TARGET=_blank>http://personalpages.tds.net/~pdieten</A>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 6:21 am 
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Location: Circleville, OH, USA
The first 5Z4 tubes issued by RCA in 1935 consisted of 2 glass tubes each containing a plate & half the filament enclosed in a perforated metal shell. There was some technical problem that prevented an all-metal tube from being made. This problem was quickly solved.<BR>Many other companies made MG tubes because they could not afford the tooling for a true metal tube. They just used a slightly smaller glass bulb and slipped it into a metal shell.<P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 6:35 am 
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Thanks Paul, <BR>The demise of my 47LL is becoming more pronounced and I decided to test its tubes. <P>The first thing I did this past summer, immediately after I purchased it, was to replace the glass 5Y3(?) sub it came with, with a 5Z4. Thought that the sub might be a contributing factor to its low volume, distortion, high pitched oscillation and inability to pick up more than 1 station. <P>The gentleman I bought the 5Z4 tube from said that my 5Y3 was actually a 5U3 and it tested fine on his tester. I don't know how he could tell the difference between a 5Y3 and a 5U3 just by looking at it but I figured I would replace it with a 5Z4 and see if it made a difference since the radio was a weak performer to begin with. <P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 6:43 am 
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Thanks Ken, <BR>I asked that question to an "audiophile" guy and he didn't have an answer, guess that makes you smarter than "one of them". <IMG SRC="http://antiqueradios.com/forums/smile.gif"><P>Ron<P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 6:44 am 
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Paul Dietenberger wrote:
<font>quote:</font><HR>Originally posted by Ken Owens:<BR><B>The first 5Z4 tubes issued by RCA in 1935 consisted of 2 glass tubes each containing a plate & half the filament enclosed in a perforated metal shell. There was some technical problem that prevented an all-metal tube from being made. This problem was quickly solved.</B><HR>
<P>Really? Somewhere along the line I had heard that that design was crap and the tube withdrawn until the new design was done, that's why 1936 RCAs use 80 and 5Z3 tubes instead of the 5Z4......of course I have nothing to back that up......<P>------------------<BR>Paul<P> <A HREF="http://personalpages.tds.net/~pdieten" TARGET=_blank>http://personalpages.tds.net/~pdieten</A>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 6:48 am 
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Ron, possibly the radio does that because the caps are shot, not because of a bad tube. If you were to recap the set that might go away.<P>Incidentally, 5U3 is not a valid tube type number. Is it a 5U4?<P>------------------<BR>Paul<P> <A HREF="http://personalpages.tds.net/~pdieten" TARGET=_blank>http://personalpages.tds.net/~pdieten</A>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 8:07 am 
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Originally posted by Paul Dietenberger:<BR><B>...If you were to recap the set that might go away.<P></B> <P>Now that you "spilled the beans" I am going to be in serious trouble here. <IMG SRC="http://antiqueradios.com/forums/wink.gif"> I plead guilty to the charge of "failure to recap" and I promise I will "moth ball" this radio until I get some caps. <P>Since I don't have caps on hand I thought I would start with the tubes, knowing it very likely is the caps. <P>You and my tube tester confirmed what I didn't want to admit. <IMG SRC="http://antiqueradios.com/forums/smile.gif"> <P>By the way a 5U3 is so rare, it only exists on my keyboard. I should have said 5V3. <P>Ron<P> <P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 8:26 am 
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Hi Ron<P> Wouldn't expect a 5V3 to be used in any radio. It draws 3.8 amps filament current. So much tube socket pins would get hot. Finally current was reduced to 3 amps with the 5V3A.<P> Might mean 5V4G? This tube will replace a 5Z4 or 5Y3. Both 5Z4 & 5V4G have close spaced elements so B+ voltage will be higher than with a 5Y3.<P> 5Z4MG is taller than most of the subs mentioned. You can use 5Z4 or 5V4G which are both more reliable.<P> <P>------------------<BR>Norm


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 9:46 am 
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O.K. Here's my story and I'm stickin' to it. <P>I went and checked the old tube...it had 5V4 written on it with a marker. Therefore, I believe I was told it was a 5Y4. Sorry for the confusion.<P>In any case, I had no idea what the glass tube really was, so I decided to replace the glass "mystery tube" with the NOS National union 5Z4 metal tube I purchased the day after I got the radio. It tested great and I got to experience the smell of the new paint as it was heated the first time I used it. I will never forget that "new metal tube smell" but sadly it is no longer there. <P>Is there a way I can find out what the glass tube is for sure? <P>Ron<P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 10:24 am 
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5Y4 is electrically the same as a 5Y3 but has different pin connections and they are not interchangeable without rewiring the socket.<BR>Don Black.<P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 7:19 pm 
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The Chart O' Rectifiers:<P> <IMG SRC="http://personalpages.tds.net/~pdieten/rectifiers.gif"> <P>Base type 4C is the standard 4-pin base, 4AD is the same thing with a separate heater and cathode. They can generally be interchanged, though the B+ levels may change.<P>Base type 5T is the base type for a 5Y3, which is a filament type. 5L is the same thing with a separate heater and cathode. Again, they can generally be interchanged, though the B+ levels may change.<P>Base type 5Q is completely different and cannot be interchanged with 5T/5L without wiring changes.<P>So, generally 80, 83V and 5Z3 can be substituted for one another (if the power transformer can handle the load) and same with 5Y3/5Z4/5V4/5T4/5U4. 5Y4 and 5X4 have different pinouts and require wiring changes.<P>------------------<BR>Paul<P> <A HREF="http://personalpages.tds.net/~pdieten" TARGET=_blank>http://personalpages.tds.net/~pdieten</A>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 10:38 pm 
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Location: Portland, TX, US
While we are on the topic of rectifiers, I found two 5R4's (the same tube used in that funky power supply in a previous thread). I'm familiar with the tubes listed in Paul's "chart o' rectifiers" but I have never seen a 5R4. Anyone familiar with these?<P>------------------<BR>


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 Post subject: 5Z4MG tube
PostPosted: Nov Mon 29, 2004 11:17 pm 
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It's a 5T-base rectifier, takes 5V at 2A on the filament, will sub for 5Y3. Apparently it handles very high voltage on the plates and is used in transmitters.<P>------------------<BR>Paul<P> <A HREF="http://personalpages.tds.net/~pdieten" TARGET=_blank>http://personalpages.tds.net/~pdieten</A>


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 Post subject: 5Z4MG tube
PostPosted: Dec Thu 02, 2004 12:54 pm 
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Location: Cedar Rapids, Iowa, USA
Type 5R4G, etc., were extensively used in military rigs. They were like a slightly derated 5U4G, but were built to withstand operation at high altitudes, so were good for applications in aircraft. <P>------------------<BR>


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